The present invention relates to detent mechanisms and pertains particularly to pre-assembled detent mechanisms for retaining hydraulic valve spools in preselected positions.
Detent mechanisms for holding valve spools in preselected positions are well known in the art. Such detent mechanisms normally consist of a plurality of elements which are separately and individually assembled in a bore in the valve housing extending transversely to the valve spool. Such assemblies normally have numerous disadvantages. For example, when it is desired to remove the valve spool it is necessary to disassemble the detent mechanism, otherwise the detent plunger and spring will be forced into the valve bore. It will also be appreciated since the parts of the detent mechanism are not pre-assembled, the assembly will be cumbersome and time-consuming because each separate part must be handled separately and inserted in proper sequence. It will also be appreciated if such parts may also be lost or misplaced during the assembly or disassembly of the mechanism.
While pre-assembled detent mechanisms are known, such mechanisms are encased in capsule-like fashion in a housing. Such assemblies have the disadvantage of requiring considerable space to accommodate the extra housing and retaining means. Attempts to reduce the space required for such assembly normally provide a mechanism which fails to include sufficient guide means for the detent plunger. Consequently, side loading imposed on the plunger by attempted movement of the spool tends to cocking or tilting of the plunger, causing it to bind or hang up in the bore and causing considerable force to be required to move the valve spool. The binding of such mechanisms also tends to vary, resulting in differences in operator feel and consequent inconsistent control of the hydraulic control valve.
The prior art is exemplified by the following U.S. Pat. Nos.: 2,984,258 issued May 16, 1961 to Clary; 3,285,284 issued Nov. 15, 1966 to Junck et al.; and 3,339,584 issued Sept. 5, 1967 to Long.